Incandescent lamps offer the advantage of being cheap to produce since the production method used is mature and fully automated. Incandescent lamps do however have a large quantity of generated heat, a high power consumption and a short life. In the constant striving towards new technologies providing a lower power consumption it is therefore interesting to find suitable replacements. This is especially the case since the production of incandescent lamps recently has been limited or even stopped due to its inefficient energy consumption.
One alternative to the incandescent lamp is the LED based lamp. The LED based lamp has a small quantity of generated heat, a low power consumption and a long life. Compared to incandescent lamps, which parts are mature and cheap due to fully automated manufacturing processes, LED based lamps and their parts are still evolving as their design and way of assembly is not yet mature and also the volumes are so far not very high. This makes the parts relatively expensive and also urges manual assembly to low labor regions with a complex supply chain with long lead times. There is a tendency that the LED based lamps are designed around the LED source. Further, a LED based lamp does in general consist of more parts to assemble as compared to incandescent lamps. While a incandescent lamp consist of a burner stem with a tungsten filament, a glass bulb and a cap, a typical LED based lamp consists of a plurality of LED's on a PCB (printed circuit board), a driver to feed the LED's, a heatsink to limit the LED temperature, a housing, a plastic bulb, screws and a cap.
Also, a plurality of LED's are required to provide the required light quantity. The LED's are typically arranged on a driver PCB and the number of LED's are adapted to the wanted light quantity. This is however problematic when assembling the driver PCB and the bulb since the opening of the bulb must be large enough to receive the driver PCB. There is also a problem of dissipating the heat generated by the LED's in order of ensuring an acceptable life time.
US2004/0008525 discloses one solution to this problem in which a LED chain body is formed by connecting a plurality of LED lamps via flexible members. The LED chain body is inserted into the bulb. The number of LED's in the chain body may be adapted to the desired quantity of light.
WO05/090852 discloses a lighting element comprising a housing with a substrate including a plurality of light emitting devices. The substrate, initially having a planar form, conforms to the inside wall of the housing when inserted therein. Standoffs are provided between the substrate and the inside wall to provide a desired light dispersion.